Charles Darwin admired the earthworm extravagantly. "It may be doubted," he wrote in 1881, "if there are any other animals which have played such an important part in the history of the world as these lowly organized creatures." The earthworm is a natural organic chemist, cultivator, and fertilizer. But it may have yet another talent, one that Darwin would never have discovered: toxic cleanup specialist. It turns out that PCBs -- among the nastiest of modern pollutants -- may be no match for the humble earthworm.
In addition to their toxicity (the Environmental Protection Agency has designated them a probable human carcinogen), polychlorinated biphenyls are notorious for two reasons. First, they "bioaccumulate." In other words, their concentration in tissue increases dramatically as they move up the food chain. Second, they are virtually indestructible.
For half a century, until their use was banned in 1979, PCBs were regarded as a miracle of the industrial age. With their stability, low volatility, and extreme fire resistance, they made wonderful insulators for electrical transformers and capacitors. Their largest user was General Electric, whose plants in New York State and Pittsfield, Massachusetts, discharged massive amounts of PCBs into the Hudson and Housatonic rivers. A series of consent decrees in the 1990s obliged G.E. to spend hundreds of millions of dollars to clean up the mess it had left behind. But the settlements left a large question unanswered: How was this to be accomplished?
There are two basic alternatives for disposing of PCBs. One is incineration, the other dumping in hazardous-waste landfills. Both methods are expensive and controversial. At the G.E. facility in Pittsfield, for example, one of the largest landfills used for PCB-contaminated soil is Hill 78, which looms high above the Allendale Elementary School.
Tim Gray, who was trained as a chemist and biologist before becoming executive director of the Housatonic River Initiative, has been battling G.E. for years. Sites like Hill 78 keep him awake at night.
So when Gray learned of the work of a Slovak scientist named Oto Sova, he was excited. Sova was using the Californian earthworm, Eisenia foetida -- or ground-up earthworm enzymes, to be precise, in a solution called Enzymmix -- to remediate soils contaminated with petroleum derivatives or, most ambitiously, toxins such as phenols, cresols, DDT, and even PCBs. Better yet, Enzymmix promised to work in situ, either by being sprayed directly on contaminated surfaces or by being injected into the ground through plastic tubes.
Sova's remedy has been successfully tested at gas stations, on airport runways, and at other contaminated sites in five European countries. "I didn't know if this was for real or if it was too good to be true," Gray says. So he went to Europe to observe the enzymes in action. He was impressed enough with what he saw to take soil samples from G.E.'s Pittsfield site to be tested at the State University of New York at Albany and at HydroTechnologies, a private environmental laboratory in New Milford, Connecticut.
HydroTechnologies' lab director, Lawrence Paetsch, tested two different soil samples, with PCB levels of 250 and 450 parts per million (ppm) respectively. (The EPA considers anything above 50 ppm to be hazardous.) Paetsch says that a single application of the enzymes "showed a significant reduction in PCB concentration: On average, 62 percent of the original PCB content was removed." A second round of tests showed 76 percent removal.
If Sova's earthworm cocktail is to be approved for use in the United States, the next step is for it to be tested by the EPA's Superfund Innovative Technologies Evaluation Program (SITE). Tim Gray is optimistic. "When I went to Europe," he says, "I was about 1 percent convinced. Now I'd say I'm 80 percent there."